Let's get to the latest on the so-called breakup murder trial. Jodi arias facing a withering cross-examination thursday. The prosecution, taking direc aim at her credibility. Abc's ryan owens is in phoenix, arizona, with the very latest. Ryan, good morning. Reporter: Good morning to you, amy. All of a sudden, we met a brand-new jodi arias. Forget that soft-spoken, sobbing woman we got to know on the stand the past eight days. She was replaced by a smiling, sometimes smug defendant, who was ready to fight for her life. Jodi arias debuted a new look for her big day, a black business suit. And she meant business. Sparring with veteran prosecutor, juan martinez, on his first day of cross-examination. Do you have problems with your memory, ma'am? Sometimes. Reporter: Martinez grilled her about not remembering she stabbed her ex-boyfriend in june of 2008. I have no memory of stabbing him. Reporter: All arias seems to remember now is she killed in self-defense, after claiming alexander attacked her. What factors implement your having a memory problem? Usually when men like you are screaming at me or drilling me. That affects your memory problems, right? It does. It makes my brain scramble. Reporter: Martinez tried to rattle her. Frequently smiling at the man who wants her sentenced to death. The prosecutor says she plotted the murder of her ex-boyfriend and repeatedly lied to cover her tracks. He believes one of her biggest lies is that she's an abused woman. Arias says her crooked finger is evidence of that. She blames months before she killed alexander, he broke her finger. Show us how bent it is again. Reporter: But martinez believes she injured her finger while she was shooting and repeatedly stabbing them. To make the point, he showed this picture of arias' perfectly healthy looking hand months after alexander supposedly beat her. That didn't phase the newly-confident arias, either. You don't have a bent finger here. My finger is bent there. You're saying your finger is bent there? Yes. Reporter: Jodi arias has been on the stand for so long, to be honest, the jury was starting to get bored. Not when cross-examination started. They stopped taking notes. They looked right from jodi arias, back to the prosecutor and back to jodi arias. It was like they were looking at a tennis match, amy. And this will continue on monday.

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